The present disclosure relates to a self-operated regulator (controller without auxiliary power) for controlling a stream of working fluid, in particular of a processing plant such as a plant consisting of gas suppliers, hot water suppliers, and in particular waste water suppliers and/or heat suppliers, or a heating and/or cooling system in particular for a property, a district heating system or the like, or of a plant for heating and cooling process fluids, in particular industrial process fluids. Self-operated regulators are also used in explosion-hazardous plants because the lack of additional auxiliary power brings about a significant reduction in the risk of explosion.
A self-operated regulator requires no external energy supply to operate the regulator, in particular no electronic power supply and no pneumatics, such as no external pneumatic continuous pressure supply, to implement the pre-adjusted or variable open-loop or closed-loop control algorithm. The self-operated regulator comprises a control valve and a control actuator configured for mechanically operating the control valve, wherein the supply of energy for the provision of an operating force for actuating the control valve is obtained exclusively from the stream of working fluid which is to be adjusted, or from the working fluid itself. This differentiates a self-operated regulator for process plants from a regulator operated by auxiliary energy in the fact that no additional controllable operating energy (in addition to the energy already existing in the working fluid or in the working fluid stream), such as electric power or pneumatics, must be added to the regulator to be able to complete its actuation task, as well as its measurement and/or control function.
The open-loop/closed-loop control of a regulator for a processing plant comprises in particular only three essential functions, namely measuring a control variable, regulating the control variable, and implementing the control movement in accordance with a regulation and/or control routine. Since the self-operated regulator requires no external auxiliary power supply, the operating costs and the installation costs are low, on account of the absence of an additional power supply.
The exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.